blob: db4abd2682fcfd107fc2af1c1b4bbf6d377feb89 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
|
// SPDX-License-Identifier: GPL-2.0
#ifndef BPF_NO_PRESERVE_ACCESS_INDEX
#define BPF_NO_PRESERVE_ACCESS_INDEX
#endif
#include <vmlinux.h>
#include <bpf/bpf_core_read.h>
#include <bpf/bpf_helpers.h>
#define INLINE __always_inline
#define skb_shorter(skb, len) ((void *)(long)(skb)->data + (len) > (void *)(long)skb->data_end)
#define ETH_IPV4_TCP_SIZE (14 + sizeof(struct iphdr) + sizeof(struct tcphdr))
static INLINE struct iphdr *get_iphdr(struct __sk_buff *skb)
{
struct iphdr *ip = NULL;
struct ethhdr *eth;
if (skb_shorter(skb, ETH_IPV4_TCP_SIZE))
goto out;
eth = (void *)(long)skb->data;
ip = (void *)(eth + 1);
out:
return ip;
}
SEC("tc")
int main_prog(struct __sk_buff *skb)
{
struct iphdr *ip = NULL;
struct tcphdr *tcp;
__u8 proto = 0;
if (!(ip = get_iphdr(skb)))
goto out;
proto = ip->protocol;
if (proto != IPPROTO_TCP)
goto out;
tcp = (void*)(ip + 1);
if (tcp->dest != 0)
goto out;
if (!tcp)
goto out;
return tcp->urg_ptr;
out:
return -1;
}
char _license[] SEC("license") = "GPL";
|
